Step 18: Install the Extruder Stepper problem

wesc

Step 18: Install the Extruder Stepper problem

Post by wesc » Wed Aug 02, 2017 12:47 pm

On my extruder, the shaft flat protruded into the drive gear such that the set screw beared partially on the round portion of the shaft. This caused the drive to shift several mm axially out when tightening the set screw.

I first tried to fix by inserting washers on the screws holding the motor to the extruder, but it wasn't enough.

Fix was to flip the drive gear around. Seems this should be ok.

Also, I used a drill bit to align the drive groove as you neeed the 1.5mm driver to tighten the set screw. Without the bit locking it in the drive gear shifted a hair when tightening the set screw

User avatar
UltiBots
Posts: 602
Joined: Fri Apr 21, 2017 10:18 am

Re: Step 18: Install the Extruder Stepper problem

Post by UltiBots » Wed Aug 02, 2017 4:46 pm

Please post pictures of your extruder. This doesn't seem standard. I will look at step 17 for possible edits.
Brad - UltiBots LLC

User avatar
JustDave
Posts: 45
Joined: Tue Apr 25, 2017 12:08 am
Location: Woodland, CA

Re: Step 18: Install the Extruder Stepper problem

Post by JustDave » Wed Aug 02, 2017 7:34 pm

I know what you mean, I broke off one of the motor mounts trying to figure this out. Then I re-read the previous step and it does say to back off the set screw enough so that you can insert the motor such that the set screw lands on the round part of the shaft, not the flat. Or at least that's how I interpreted it when I got it to finally work. I think with the drive gear turned the other way, the idler bearings in the main body do not have anything to ride upon.

wesc
Posts: 26
Joined: Wed Aug 02, 2017 7:58 pm

Re: Step 17: Install the Extruder Stepper problem

Post by wesc » Wed Aug 02, 2017 8:10 pm

Links to pics showing the problem:

http://imgur.com/a/XIWHP

Dave, you are right - the idlers don't bear on the gear. It can't be right for the screw to bear upon the non-flat portion of the shaft though!

wesc
Posts: 26
Joined: Wed Aug 02, 2017 7:58 pm

Re: Step 17: Install the Extruder Stepper problem

Post by wesc » Wed Aug 02, 2017 8:13 pm

The other possible fix is to insert some washers between the motor and the extruder body and use longer screws.

I had to use a 30mm screw for the top mount. 25mm worked for the lower.
http://imgur.com/npds29v
http://imgur.com/hAjOCXy
Last edited by wesc on Wed Aug 02, 2017 8:40 pm, edited 1 time in total.

User avatar
JustDave
Posts: 45
Joined: Tue Apr 25, 2017 12:08 am
Location: Woodland, CA

Re: Step 17: Install the Extruder Stepper problem

Post by JustDave » Wed Aug 02, 2017 8:32 pm

I was thinking of grinding more "flat" on the motor shaft. As far as adding spacers between the motor and the extruder; guess how I broke the motor mount?

PS: Your dial indicator micrometer is cool, but it is dirty!

wesc
Posts: 26
Joined: Wed Aug 02, 2017 7:58 pm

Re: Step 17: Install the Extruder Stepper problem

Post by wesc » Wed Aug 02, 2017 9:02 pm

JustDave wrote:
Wed Aug 02, 2017 8:32 pm
As far as adding spacers between the motor and the extruder; guess how I broke the motor mount?

PS: Your dial indicator micrometer is cool, but it is dirty!
It should be good with the washers. Did you put the spacer around the shaft, leaving the ears cantelevered?

I'm embarrassed to say that Mitutoyo dial caliper ended up spending some time on my welding table. Quite remarkable that it is still smooth and accurate...

User avatar
JustDave
Posts: 45
Joined: Tue Apr 25, 2017 12:08 am
Location: Woodland, CA

Re: Step 17: Install the Extruder Stepper problem

Post by JustDave » Wed Aug 02, 2017 11:12 pm

Ding ding ding: we have a winner! I cut a spacer out of thick plastic, but it did not protrude far enough over one of the mounting points.

Just ribbing you about the caliper; good to see analog still in action. :geek:

User avatar
UltiBots
Posts: 602
Joined: Fri Apr 21, 2017 10:18 am

Re: Step 18: Install the Extruder Stepper problem

Post by UltiBots » Thu Aug 03, 2017 7:48 am

Hi All - I see the issue. NMB Minebea has made 2 PG35L motors for UltiBots.

Motors with a data label PG35L-D48-UBS7 have 18mm shafts and MATCH step 17 in the guide.
Motors with a data label PG35L-D48-UCH4A have 20mm long shafts and are not compatible with step 17 in the guide.

A temporary solution... do NOT to use the "D Flat" for the set screw. Allow the set screw to bite into the round part of the shaft. This will allow you to use your printer once assembled. Or if you have proper tools, extend the "D Flat" with a grinder or file. Don't let the shaft get too hot if grinding.

We are working on a modified body for the UCH4A motor. If you have the UCH4A motor please email sales )at( ultibots dotcom for further assistance.
Brad - UltiBots LLC

wesc
Posts: 26
Joined: Wed Aug 02, 2017 7:58 pm

Re: Step 18: Install the Extruder Stepper problem

Post by wesc » Thu Aug 03, 2017 2:24 pm

Thanks for clearing this up. Is there any reason why my double washer 2mm spacer fix won't work?

Post Reply